Multi-Transcripts and Expressions of Trypsin Inhibitor and α-Amylase Inhibitor Genes of Sengon (Falcataria falcata) Against Xystrocera festiva Stem Borer Infestation

The infestation of boktor (<i>Xystrocera festiva</i> Pascoe) stem borer in Sengon (<i>Falcataria falcata</i>) tree plantations in Indonesia, especially in Java, has caused severe losses by damaging the stems, decreasing wood quality, and potentially leading to mortality. To digest the woods, the <i>X. festiva</i> larvae's gut has at least two digestive enzymes, which are trypsin and α-amylase. Former studies have shown that <i>F. falcata</i> produces inhibitors of these two enzymes as part of its defense mechanisms. This research aimed to analyze <i>trypsin inhibitor (TI)</i> and <i>α-amylase inhibitor (AAI)</i> transcripts, as well as their expression, in <i>X. festiva</i>-infested and resistant <i>F. falcata</i> trees. We found 19 contigs encoding the <i>TI</i> gene and 29 contigs encoding <i>AAI.</i> The results were able to predict the sequence of the DNA that produced the <i>TI</i> and <i>AAI</i> transcriptomes, which proved that one gene could be expressed differently due to alternative splicing. The DEG analysis and RT-PCR confirmed that mostly the <i>TI</i> and <i>AAI</i> activity was heavily induced by the <i>X. festiva</i> larvae attacks. The expression of the <i>TI</i> gene was upregulated 0.78 times, while the <i>AAI</i> gene expression was upregulated 2.44 times in infested samples. The findings from this study are fundamental in understanding the mechanism of <i>F. falcata</i> resistance against <i>X. festiva</i> infestation and selecting the resistant trees.